Motor-controlling device



` B. S. IKMAN Morn coNrnoLLrNG DEVICE 1919 2 Sheen-snee: 2

Original Filed Oct. 14.

Q m" m* www ATTORNEY Patented Oct. 28, 1924.

UNITEDf STATES PATENT OFFICE.

BURTON S. AIKMAN, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO NATIONAL BRAKE &

ELECTRIC COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF WIS- CONSIN.

'MoToR-coNTnoLLrNG DEVICE.

vOriginal application ilerd October 14, 1919, Serial No. 330,601. Divided and this application` led January 24, 1921.

To all whom it may conce/m:

Be it known that I, BURTON S. AIKMAN, a citizen' of the United States, residing at Milwaukee, in the co-unty of Milwaukee and State of Visconsin, have invented new and useful Improvements in Motor-Controlling Devices, of which the following is a speciication.

This invention relates to electric motor controlling devices and more particularly to a safety device for protecting the motor, this application being a division of my pending application, Serial No. 330,601, filed October 14, 1919.

The principal object of my invention is to provide means for protecting` the motor, while running, against excessive flow ofcurrent in the motor circuit.

Other objects and advantages will appear in the following' more detailed description of the invention.

In the yaccompanying drawings; Fig. 1

is a central sectional view` of'a -motor con-- trolling device embodying my improve ments, and showing the parts inthe'switch open position; Fig.- '2 a view similar to Fig.

1, showing the parts in position with the f switch closed and the 'resistance short-circuited; Fig. 3 a View of a portion of the mechanism shown in Fig. 1, `showing a switch closed and operating through a resistance; Fig. 4 an elevational view of the motor controlling device; Fig. 5 a wiring diagram, showing the circuit connections in the open position of the switch; Fig. 6a wiring diagram, showing the circuit connections with the switch closedv and operat-y ing through a resistance; and Fig. 7 va wiringl diagram, showing the switch closed with Vthe resistance short-circuited.

VVAs shown in the drawings, the apparatus may comprise a motor controlling device 1, having a chamber 2 connected to a cylinder 3A containing a piston 4 for operating, through a ystem 5, a suction valve 6 of a fluid compressor. y

The casingof the motor controlling device 1 has a .piston Achamber 7, containing afpiston Sand provided with a piston stem 9.

VArranged on opposite sides of the piston stem 9 kare two main switch arms 10, each having a contact 11 adapted'to first engage Serial No. 439,392.

a corresponding yielding contact 12 and then a corresponding fixed contact 13. Each main switch arm 10 is pivctally connected to an auxiliary switch arm or lever 14, said members being pivotally connected to the controller casing, and having a common depending latch member 15 pivotally connected to the piston stem 9 at opposite connected to the outer ends ofthe levers 14.

The switch arms 10 and 14`are pivotaliy sides by means of Heating pins 16, adapted to work in slots 17 and 18 of the respective switch arms 10 and 14 and a slot 19 in the piston stem 9. A coil spring 2O mounted in pockets provided in the switch arms 10 and 14 tends to yieldingly hold said arms apart, as shown in Fig. 2.

Mounted on the controller casing are two magnet coils 21, each having an Varmature 22 providedY with a projection 23 adapted to engage the latchV 15. j v

Mounted centrally below the magnet coils 21 is another magnet coil 24 having an armature 25, adapted to act as a stop for the latch 15 and adapted to operate a double beat valve 26 through a stem'27.

The piston chamber 7 is connected by passage 28v with a chamber 29, containing a valve 30 adapted in one position to establish communication from pist-cn chamber 7 to exhaust port 31 and in another position from said chamber to a iiuid supply passage 32, controlled by the double beat valve 26. i

Secured to the motor controller casing is a pump governor 39 of any desired construction and shown in the drawings as comprising a movable diaphragm 33, subject on one side to the pressure in theiusual storage reservoir into which the compressor or pump compresses fluid, said'tluid being supplied thereto through pipe 34 and passage 35, and on the opposite side to the pressure of an adjustable spring 36.

The movement of the diaphragm 33 is adapted to be transmitted to an arm 37 for operating a movable contact 3S, which controls the circuit of the motor which operates the finid compressor.

In Vthe design illustrated in the drawings, the construction is adapted for a motor of the squirrel cage type, and employing a resistance in two legs of the primary circuit. 1f, however, it is thought desirable, aresistance maybe provided for each of the three legs of a three phase circuit.

It might also be stated here that the constructionV may be readily adapted for a motor of the slip ring type.

Vhere the construction is designed for controlling a resistance in two legs of the primary circuit, there is provided a switch controlling mechanismv for the resistance in each leg, as hereinbefore described and as shown in the wiring diagrams; Figs. 5 to 7 inclusive. v p

`manually operated lever 40 is provided which Vis adapted to operate a finger 41; and the `piston stem 9 is provided with a pin 42 ,adapted to be engaged by the linger 41.

In operation, when there is little or no duid pressure in the storage reservoir and it is desired to start the compressor, the handle is moved to its full upward position, as shown in Fig. 3 of the drawings. This movement causes the finger to engage pin 42 and lift the piston stem 9. The main and auxiliary switch arms 10 and 14 are then lifted through the floating pins 16, so that the contacts 11 engage the yielding contacts 12, but not suniciently to engage the fixed contacts 1.3, as shown in wiring diagram, Fig. 6. A

' V'resistance element 43 is then connected into two -legs of the primary circuit of the motor.

Since there is little or no pressure in the reservoir, the pump governor 39 will operate so that contact 38 willclose ashunt circuit through the coil 24 causing armature 25 to move to its closed position.

One switch arm 10 connects one resistance element 43 through the corresponding magnet Coil 21 with one leg of the primary circuit ofthe motor, while the other switch arm connects another resistance element 43 through the correspondingV magnet coil 21 withl another leg of the primary circuit, as shown in thewiring diagrams. l

The heavy initial inrush of current through the coils 21, causes the armatures 22 toV move forward, so that the projections 23 of theY armatures 22 engage the latch 15,

moving Zthe same forward, so that the latch will not engage its seat on the armature lever 44. Y

,The lever 40 must he held in its full upward position until the motor has reached a speed such that the current flow in theV coils 21 will be insuiiicient to hold the arma-tures 22 in closed position. Then the armatures 22 willA drop back bygravity.V The lever 40, may -now be released and the latch 15 will Seaton the arm 44. Y

The latch 15 and the auxiliary switch arms 14 will`V thusv be prevented from moving downwardly, but piston 8 will be permitted tomlove downwardly through the action ofY the' spring 49.

The auxiliary arms 14 being now fixed in position by latch 15, the'downward movement of piston 8 moves the main switch arms 10, compressing the springs 20, so that the contacts 12 will be pressedupwardly, permitting the contacts 11 to engage the contacts 13, thus short-circuiting the-resistance 43 in each leg of the circuit, as shown in Figs. 1 and 7;

In this position of therparts, the magnet coil 24 being in a. shunt circuit with the motor, is energized, so that armature 25 is in position for holding the stem 27 and double beat valve 26 with communication closed from 4the storage reservoir pipe 34 to chamber 2, while communicationy is; open vfrom said chamber through passage 45 to passage 32 and thence to vthe atmosphere through a port 46 in the valve 30. p c

The compressor is now operated by the motor to compressfiuid into the storage reservoir, and when the pressure in said reservoir has been increased to a. predetermined degree, the diaphragm 33 of the pump govf ernor 39 is operated by reservoir pressure to throw the switch contact 38, so ask to open the shunt circuit containing coil 24, allow- Vthe magnet 24, the-stem 27 will, befree to move, permitting the Ydouble" beat `V valve- 26 to be Amoved byreservoir ,pressure sothat communication is opened from the .reservoir pipe 34 to passage 45, permitting the chamber 2 to be charged with fluid atfres'ervoir pressure and causing' the piston 4y to be op-` erated so as to open the inlet valve' 6 ofthe compressor through t-he Stem5, thus rendertive.

When thepressure in the storage reservoir has fallen to a predetermineddegree,VV the pump governor diaphragm 33 Vwill be operated to permit the spring 36, to shift the contact 38 Vto its closed position, thus closing the shunt circuit through the; coil 24. Y. Y

The armature 25 will thenfbe Vmoved toward the coil 24, causing the stem 27 to operate the double beat valve 26, soas to Aout ofi-the reservoir supply passage 35 and connect passage 45 with passage 32. f

Since at this time', thechamber 2 ,contains Y fluid at reservoir pressure,^'fluid from said. chamber will How to valve 30, forcing Vsame to its outer position, in whichcommunic'ation is opened, softhe fluid canl fio'wfroi'n the' chamber 2 to the piston chamber 7. l Y .f

Piston 8 is thereupon moved to its extremeV upper position causing the switch arms l to be moved so that the contacts 11 engage the contacts 12. This closes the motor circuit through the resistances 43, as hereinbefore described, starting the motor.

The coils 21 are then initially energized with the rush of current in starting so as to attract the armatures 22, rendering the latch 15 ineffective and also closing the eX- iaust port 47 to the piston chamber 7.

As soon as the motor speeds up, the current falls sufficiently to permit the armature 22 to drop away, thus opening the exhaust port 47 to the piston cylinder 7.

The piston 8 will then be moved downwardly by the spring 49, and since the latch 15 will now engage the arm 44, the movement of the piston 8 will operate the switch arms to connect the contacts 11 and 13 and thus short-circuit the resistances 43.

The pressure in chamber 2 and the unloading cylinder 3 will also be rapidly vented through the port 47, until the pressure has fallen sufficiently to permit spring 48 7 to move the valve 30 and thereby open a direct atmospheric vent from the piston chamber 7 to the exhaust port 31.

The fluid pressure on the unloading piston 4 being relieved, the suction valve 6 will.

be permitted to close and allows the compressor to operate under load.

It will be noted that the time between the starting of the motor and the loading of the compressor is governed not only by the curl' rent input of the motor but also by the time necessary to exhaust the fluid pressure from the unloading cylinder. This ensures the motor being at full speed before imposing the load on the compressor.

Should there occur an interruption of the line circuit between the cutting in and cutting out points of the governor, the action of restoring the parts to their off or open positions and the unloading of the compres- V sor will be accomplished in the same manner wardly and cause the switch arms to open the motor circuit.

The starting resistance is protected by means of the blow down port 46 through valve 30, since if the motor fails to start, the pressure will be depleted through this port to a point suiiicient to allow spring 48 to open valve 30, after a time well within the safe limits necessary to protect the resistance against burn out and since the latch during this period will be rendered ineffective by the movement of armatures 22, it will be readily seen that when the valve opens, the switch portion will also promptly open.

Having now described my invention, what I claim as new, and desire to secure by Letters Patent, is

In a motor controlling device, the combination with a switch for controlling the motor circuit and including a'movable switch arm, of a lever connected to said arm, a depending latch member pivoted to said lever, a magnet, a pivotally mounted armature therefor and providing a support for said member to hold the switch arm in its closed position when said magnet is energized, a second magnet, and a pivotally mounted armature therefor having means for engaging and tripping said latch member from its support when said second magnet is subjected to an excess flow of current.

In testimony whereof I have hereunto set my hand.

BURTON S. AIKMAN. 

